Patent EA-002709-B1 (EA)
Title: Method of formulating alkali metal salts
Inventor: PHINNEY ROBIN
IPC: C01D7/02
Filed: 1999-09-30
Abstract: 1. A method of formulating food grade sodium bicarbonate and potassium sulfate, comprising the steps of: a) providing a source of liquid sodium sulfate; b) providing a source of ammonium bicarbonate to precipitate sodium bicarbonate; c) contacting said sodium sulfate and said ammonium bicarbonate; d) precipitating sodium bicarbonate and forming a liquor; e) filtering said sodium bicarbonate; f) saturating liquor from step e) with sodium sulfate; g) contacting said liquor with ammonium carbonate ammonia gas or carbon dioxide to precipitate further sodium bicarbonate; h) filtering precipitated sodium bicarbonate from step g); i) combining sodium bicarbonate precipitate from step e) and h) and washing to form food grade sodium bicarbonate; j) cooling liquor from step i) to 0 degree C to at least form Glauber's salt precipitate; k) treating liquor from step j) with sulfuric acid to convert carbonate minerals to sulfate minerals and release carbon dioxide gas; l) heating liquor from step k) to between 30 degree C and 40 degree C; and m) precipitating potassium sulfate by contacting said liquor from step l) with potassium chloride. 2. The method as set forth in claim 1, further including the step of separating precipitated potassium sulfate and washing with potassium chloride. 3. The method as setforth in claim 2, further including the step of treating liquor from said step of separating precipitated potassium sulfate with lime to liberate ammonia gas. 4. The method as set forth in claim 3, further including the step of recycling said ammonia gas to step g). 5. The method as set forth in claim 4, characterized in that the method further includes the step of evaporating filtrate from claim 4. 6. The method as set forth in claim 1, characterized in that said sodium sulfate has a specific gravity of between 1.30 and 1.34 at 40 degree C. 7. The method as set forth in claim 1, characterized in that said liquor from step d) has a specific gravity of 1.25 and contains, by weight, 10.4% sodium sulfate, 17.1% ammonium sulfate, between 8% to 12% sodium bicarbonate and an excess of ammonium bicarbonate. 8. The method as set forth in claim 1, characterized in that said sodium sulfate from step e) comprises Na2SO4 x10 H2O. 9. The method as set forth in claim 1, characterized in that said liquor from step f) has a specific gravity of 1.285 at 40 degree C. 10. The method as set forth in claim 1, characterized in that said liquor from step k) is a saturated liquor of sodium sulfate, ammonium sulfate and sodium bicarbonate. 11. The method as set forth in claim 1, characterized in that said potassium sulfate is generated in a yield of at least 80% with a purity of at least 98%. 12. The method as set forth in claim 1, characterized in that said potassium sulfate is generated in a yield of at least 80% with a purity of at least 98%. 13. A method of formulating food grade sodium bicarbonate and potassium sulfate, characterized in that the method comprises the steps of: a) providing a source of liquid sodium sulfate; b) providing a source of ammonium bicarbonate; c) contacting said sodium sulfate and said ammonium bicarbonate; d) precipitating sodium bicarbonate and forming a liquor; e) precipitating sodium bicarbonate and forming a liquor by contacting said liquor from step d) with sodium sulfate; f) saturating said liquor from step d) with sodium sulfate; g) filtering solids from said liquor of step e); h) contacting said liquor from step f) with sulfonic acid to precipitate carbonates; i) cooling said liquor from step h) to 0 degree C to form Glauber's salt precipitate; j) heating said liquor from step I) to between 30 degree C to 40 degree C; and k) treating said liquor from step j) with potassium chloride to precipitate potassium sulfate; l) evaporating liquor from step k) to recover potassium values for recycling to step k); and m) drying said potassium sulfate. 14. The method as defined in claim 13, further including the step of treating liquor remaining from step I) with lime and ammonium chloride. 15. The method as defined in claim 14, wherein ammonia gas is liberated and recycled. 16. The method as defined in claim 13, wherein used potassium chloride solution is recycled to step k).